1. Field of the Invention:
This invention relates to electrical connection devices and more particularly to an outlet plug adapted to be mounted in an electrical wall outlet and into which a plurality of the electrical cords of appliances may be connected in planes at right angles to the plane of the wall outlet.
2. Prior Art:
Conventional electric service outlets installed in the walls are usually provided with a pair of double-pronged electric sockets. These sockets are adapted to receive the prongs known as contact fingers of appliance cord plugs in order to connect the appliances to the source of electricity. Since the number of common household appliances has considerably increased in recent years, the two sockets found in conventional wall outlets are often insufficient to fill the needs.
It has thus become common practice to utilize multiple socket attachments having a pair of main prongs receivable in the sockets of the wall outlet and which are electrically connected to the multiple sockets of the attachment into which appliance cords are insertable.
Most of these attachments have their multiple sockets located at the outer face of the casing, the plugged-in appliance cords thus projecting from the casing at a direction, normal or nearly normal, to the wall of the room.
Because of the inherent thickness of the multiple socket attachments, the plugging of multiple appliance cords results in an unsightly display. Furthermore, since the appliance cords extend in loops from the sockets, furniture which is often positioned in front of electrical wall outlets to hide their unesthetical aspects, must be placed at a substantial distance from the wall.
In addition, since the appliance cords project at right angles from the multiple socket attachments, that is, parallel to the main prongs, attempts at pulling out a cord from the assembly could easily result in inadvertent removal of the entire assembly from the wall outlet.
To circumvent the above-mentioned disadvantages, various multiple socket attachment, having their sockets at right angles to the plane of the main plug-in prongs and thus parallel to the plane of the wall have been developped.
Examples of such devices are disclosed in U.S. Pat. Nos. 2,761,113, 3,005,179, 3,061,716 and 3,156,515. The above-mentioned multiple socket attachments however present inherent structural deficiencies which tends to render them either potentially unsafe or relatively expensive to manufactures.
U.S. Pat. No. 2,761,113 discloses a multiple socket attachment which comprises a pair of rectangular plates each having a horizontal, longitudinally extending groove provided with vertical branches extending downwardly therefrom to the bottom of the plate. The mating vertical portions form sockets for receiving the prongs of appliance cords endplugs. Bus bars having depending legs are disposed in the fork-shaped grooves, the lower ends of the legs providing contact fingers. The bus bars also have integral strips which project at right angles outwardly through the back plate to serve as the main prongs.
When the plates, with their respective bus bars are joined with their respective front and rearward faces, an insulator strip must be interposed therebetween. This insulator strip is necessary in order to prevent electrical flashing or short circuiting. The patent is silent on the type of insulator strip, whether it is permanent or removable.
However, if a permanent strip, formed integrally with one of the plates is used, this will considerably complicate the molds required to manufacture the plates and will also render positioning of the bus bar into the plate more difficult during assembly.
On the other hand, if a removable type of insulator strip is used, the latter could be displaced due to the slackening of the link keeping the plates together or following a shock imparted on the device. The removable insulator strip could also be misplaced or totally omitted during assembly. Any of these situations could lead to the potential dangers resulting from electrical short circuiting of the buses.
U.S. Pat. No. 3,005,179 discloses a multiple socket attachment, wherein the symmetrical sections interlock with one another. Each section comprises partition walls defining spring contact cavities. A number of units comprising spring contacts and a prong are positioned inside each section. Even though each spring contact has its own cavity, when the sections are assembled toghether, the metal strips which interconnect the spring contacts in each section overlap each other, again creating a potential hazard for electrical flashing or short circuiting.
Furthermore, the units, because of their specific configuration, require folding operations in two separate planes during the manufacturing process.
U.S. Pat. No. 3,061,716 discloses an electro-luminescent night light combined with a multiple socket attachment. The invention comprises, amongst other components, a pair of contact strips maintained in criss-cross diagonal spaced relationship on the base of the attachment. The contact between the strips is avoided by cutting away the crossing portion. Again, a potential hazard resulting from short circuiting or flashing is inherent in the structure.
U.S. Pat. No. 3,156,515 discloses a multiple socket attachment in which the conductor strips are identically formed out of an elongated strip of material which is bent to provide three contact prong portions. Between the contact prong portions, the strip is structurally twisted so that the twisted portion is at an angle to the contact portion. The conductive strips override each other at their structurally twisted position thus again creating an electrical hazard.
Furthermore, because of the specific shape of the twisted conductive strips, the multiple plug attachments are inherently thick, thus increasing the spacing between the walls and the electrical cord appliance plug.
All of the above-mentioned patents disclose multiple socket attachments whereby the conductive material linking the sockets to the prongs are not fully surrounded by insulating material, thus creating potential hazards.
Accordingly, the present invention relates to a multiple socket attachment having its socket at right angles to the plane of the main plug-in prongs, wherein the conductive strips linking the sockets to the main plug in prongs are adequately insulated in order to prevent electrical short-circuiting or flashing.
The present invention further relates to a multiple socket attachment, in accordance with the previous object, whereby the conductive strips linking the sockets to the main plug-in prongs are identically formed during a simple and inexpensive manufacturing process. The insulating structure surrounding said strip will also be manufactured at a relatively low cost preferably by an injection moulding process.